1. Field of the Invention
The present invention relates to a wet electrographic printer, and more particularly, to a developer supply method of a wet electrographic printer, capable of controlling the concentration and level of the developer.
2. Description of the Related Art
In general, a wet electrographic printer is an apparatus for developing an electrostatic latent image, formed on a photosensitive medium such as a photosensitive belt, with a developer of a predetermined color and transferring the developed image to print a desired image. The wet electrographic printer includes a developing unit for developing an image by supplying the developer to the photosensitive medium, and a developer supply apparatus for constantly supplying the developer of a predetermined concentration to the developing unit. The developer is a mixture of a condensed ink, containing a powdery toner, with a liquid carrier, in which the toner is diluted to a concentration of approximately 2.about.4 wt %. Hereinafter, the concentration of the developer is defined by the wt % of the toner.
Meanwhile, the developer supply apparatus includes an ink cartridge for storing the condensed ink, a carrier cartridge for storing the liquid carrier, and a reservoir for storing the developer obtained by mixing the condensed ink with the liquid carrier at a predetermined ratio. Also, agitators for preventing the toner from settling out of the solution may be installed in the ink cartridge and the reservoir.
In the above developer supply apparatus, the amount of developer stored in the reservoir is reduced by the amount used to develop the electrostatic latent image of the photosensitive medium, so that more condensed ink and liquid carrier must be supplied to the reservoir to maintain the developer at a constant concentration. Also, the level of developer stored in the developer reservoir must be maintained at a constant level.
The consumption of the toner and the liquid carrier may be different according to a printed image. That is, more liquid carrier than toner is required to print a simple image or a small image, and more toner than liquid carrier is required to print a complicated image. Thus, in order to maintain the concentration of the developer at a predetermined concentration, it is necessary to appropriately supply the toner and the developer to the reservoir in accordance with the respective consumption of the toner and the liquid carrier.
The developer supply method cannot control both the concentration of the developer stored in the reservoir and the level thereof. That is, if a lot of the liquid carrier is supplied to maintain the predetermined concentration of the developer in the reservoir, the level of the developer is changed and thus undesired operating conditions may develop. On the other hand, if the level of the developer is controlled, the concentration of the developer may not be maintained at the constant level.